1. Technical Field
The present invention relates to a method of cutting glass, and more specifically, to a method of cutting laminated glass.
2. Description of Related Art
As a conventional, typical method of cutting glass, as shown in FIG. 6, the following is known: a scribe line (notch line) 62 is formed on the surface of glass 60 with a blade 61 such as a diamond blade or a super-hard blade, and thereafter, a break force (shock separation force) 63 is applied from a rear surface to cut the glass 60 along the scribe line 62.
A method of cutting glass using a laser has been also known.
A method disclosed in Patent Document 1 involves, as shown in FIG. 7, irradiating the glass 60 with an infrared laser 74 shaped in an oval shape and transmitted through the glass with relative ease, and the vicinity of a rear side of a laser-irradiated portion is cooled with a refrigerant 75 (aqueous coolant). More specifically, an initial crack is previously caused manually at a portion where the glass 60 is to be cut. Then, the laser 74 is irradiated from the portion and the vicinity of a rear side of the irradiated portion is being cooled with the refrigerant 75 in a liquid form (or gaseous form) while both of them are scanned on the glass 60. This allows the initial crack to develop in a desired cutting direction owing to the thermal distortion of the inside of the glass 60, whereby a scribe line 72 is formed. By applying a break force 73 from a rear surface of the glass 60 after the scribe line 72 is formed, the glass 60 is cut.
A method disclosed in Patent Document 2 utilizes an ultraviolet laser with high photon energy in place of the infrared laser 74 shown in FIG. 7. One ultraviolet laser beam is condensed with a lens, and a molecular bond inside glass is directly broken, whereby a scribe line is formed without causing an initial crack. Thus, the refrigerant 75 is not used. For breaking, an infrared laser is used instead of a mechanical shock.
Patent Document 3 proposes that laser light from various kinds of laser oscillators is divided in two systems, and linear laser light is applied to front and rear surfaces of a substrate. Examples of the substrate include a glass substrate and a quartz substrate for a liquid crystal display apparatus and a solar battery, and two substrates are laminated. The linear laser light forms scratching lines, i.e., scribe lines on two substrates simultaneously or successively, and the substrates on which the scribe lines are formed are irradiated with wide laser light, and thus heated and thermally distorted, whereby the substrates are separated or broken along the scribe lines. The linear laser light is shaped in a rectangular shape with a cylindrical lens array or the like.
Patent Document 1: JP 9-150286 A
Patent Document 2: JP 5-32428 A
Patent Document 3: JP 2001-179473 A